1. Field of the Invention
The present invention relates to a liquid removal apparatus, an image forming apparatus and a liquid removal method, and more particularly, to technology for removing liquid from a base material.
2. Description of the Related Art
In the related art, image forming apparatuses such as an inkjet recording apparatus and liquid electrophotography apparatus are known in which an image is formed on an intermediate transfer body by means of a liquid such as ink, liquid toner, or the like, and the image is then transferred onto a recording medium. In an apparatus of this kind, it is not possible to obtain satisfactory transfer if surplus liquid component, such as ink solvent or the carrier liquid of the toner, remains on the intermediate transfer body during transfer from the intermediate transfer body to the recording medium, and therefore the liquid component present on the intermediate transfer body must be removed before transfer.
It is suitable to use a method which brings a roller having a porous member on the surface thereof into contact with the intermediate transfer body, as a method of removing liquid from the intermediate transfer body. Furthermore, a method has been proposed in which the liquid component on the surface of the roller is recovered by setting the interior of the roller to a negative pressure in order to improve the efficiency of liquid removal.
Japanese Patent Application Publication No. 7-225516 describes a liquid absorbing roller in which the interior of a porous absorbing roller member having a hollow structure, which is formed by a porous sleeve having ventilating holes, is supported and the liquid inside the porous absorbing roller is suctioned via the porous sleeve.
Moreover, Japanese Patent Application Publication No. 2002-23504 describes a method in which a shielding body having an opening is provided inside a roller comprising a porous member on the surface thereof, the roller on the outer side with respect to the fixed opening is rotated, the interior of the shielding body is set to a reduced pressure, and the liquid absorbed in the porous body is suctioned via the opening.
However, in the liquid absorbing roller described in Japanese Patent Application Publication No. 7-225516, the suctioning pressure is distributed over the whole internal wall of the porous absorbing roller, and therefore it is difficult to achieve efficient removal of the liquid. Furthermore, in the invention described in Japanese Patent Application Publication No. 2002-23504, since there is an excessively large relative speed differential between the opening and the internal wall of the roller during the high-speed printing operation in particular, then it is not possible to achieve a sufficient suctioning time and this leads to a decline in the suctioning efficiency.